Presentation on returning from the international conference by PHD student Zhuo ZHAO
Topic： International Optics and Photonics Conference presentation
Time： Friday 9:30am, December 20,2019
Location：Room A228,West Building 5, Qujiang Campus
Presenter：Zhuo ZHAO(赵卓)
Conference Name: International Optics and Photonics Conference-2019
Conference Time： December 9-10, 2019
Conference Location： Heathrow, London, UK
Information of conference paper：
Title: Accurate Localization Method for Subaperture Stitching Interferometry in Aspherical Optics Metrology
Author: Zhuo Zhao, Bing Li, Xiaoqin Kang, Jiasheng Lu, Tongkun Liu
Abstract:
Aspherical optics have a superior performance in many applications. However, precision metrology for aspherical surface is a key stage in its manufacture. Subaperture stitching interferometry (SSI) is one of the mainstream testing methods for aspherical metrology. In many cases, the annular stitching (ASSI) is more suitable for rotational symmetry components because less motion directions need to adjust. Though motion only along optical axis need to be adjusted, inaccurate localization for subapertures may also happened due to these factors: A greater machining error in center area of optics; inappropriate zero position (Cat eye) selection in interferometry. This phenomenon will leads to a greater error in measurement result. To overcome this problem, an accurate localization method is proposed for subapertures stitching along optical axis. It is based on the maximum asphericity information between reference spherical wavefront and test aspherical surface. Firstly, by using test aspherical formula and theoretical spherical wavefront, we can calculate minimum peak-to-valley (PV) value of maximum asphericity. Theoretical location of optimal reference sphere which corresponding to this value can be obtained. Then, perform practical test which start at the original zero position and find actual minimum PV value near its theoretical location. Difference between theoretical location and actual one is the compensate quantity. Finally, execute ASSI measurement to aspherical optics. Location coordinate of each subaperture is compensated with acquired quantity. Through the experiments, it can be concluded that the proposed method can improves measurement accuracy of ASSI. The results produced by new method is more desirable than that of convention one.
